Energetics of the tetrachlorophosphonium cation, PCl 4+,g, the hexachlorophosphate anion, PCl 6−,g and metastable phosphorus (V) chloride [PCl 4+] 2[PCl 6−][Cl −,c

Abstract

Lattice potential energy calculations made on [PCl 4 +] 2[PCl 6 −][Cl −] lead to an estimate of the lattice energy of this metastable phase of phosphorus (V) chloride to be 956 kJ mol − (corresponding to 319 kJ mol − per PCl 5 formula unit). The known stability characteristics of alkali metal hexachlorophosphates enable the estimation of the enthalpy of formation of PCl 6 −,g to be in the range: −908 ⩽ Δ f H 0(PCl 6P −,g) ⩽ −896 kJ mol −1; similarly, +397 kJ mol −1 ⩾ Δ f H 0(PCl 4 +,g) ⩾ +391 kJ mol −1.